During the production of complex assemblies, such as aircraft, there is sometimes a need to monitor manufacturing operations and verify that certain operations or procedures have been properly performed. For example, aircraft landing gear may be controlled by hydraulic systems comprising hundreds of hydraulic tubes and fittings that must be assembled within a relatively small space within a wheel well. Each of these fittings may include a nut that is tightened or “torqued” by an assembly worker to a nominal torque value. Because of the large number of nuts that must be torqued, it is desirable to both monitor which nuts have been torqued, and verify that the nuts have been torqued to the correct values, since the failure to properly assemble fittings, and/or torque nuts to nominal values may result in hydraulic leaks that must be later corrected. Past attempts to monitor and verify nut torquing have involved an assembly worker painting marks on the nuts to visually indicate that they have been torqued, however this technique may be subject to human error, and in any event, may not allow verification that the nut has been torqued to the correct value.
Verifying that nuts have been torqued to the correct values may be particularly challenging where they are tightly clustered, or are located near obstructions that prevent an assembly worker from using a conventional torque-reading wrench to tighten the nuts. In these limited clearance situations, the assembly worker must use off-axis wrenches that may not provide an accurate indication of the torque value. Accordingly, the assembly worker must resort to non-precise techniques used for estimating the amount of torque needed to tighten the nut.
Accordingly, there is a need for a system for monitoring and verifying the completion of certain manufacturing operations, such as torquing of nuts, particularly in an aircraft assembly environment.